diff options
| author | Liam R. Howlett <Liam.Howlett@oracle.com> | 2023-09-21 14:12:35 -0400 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2023-09-29 17:20:46 -0700 |
| commit | 5c590804b6b0ff933ed4e5cee5d76de3a5048d9f (patch) | |
| tree | eaba1036909d61a02ee8660c003f2271b154d75c | |
| parent | 7ee29facd8a9c5a26079148e36bcf07141b3a6bc (diff) | |
maple_tree: add mas_is_active() to detect in-tree walks
Patch series "maple_tree: Fix mas_prev() state regression".
Pedro Falcato retported an mprotect regression [1] which was bisected back
to the iterator changes for maple tree. Root cause analysis showed the
mas_prev() running off the end of the VMA space (previous from 0) followed
by mas_find(), would skip the first value.
This patchset introduces maple state underflow/overflow so the sequence of
calls on the maple state will return what the user expects.
Users who encounter this bug may see mprotect(), userfaultfd_register(),
and mlock() fail on VMAs mapped with address 0.
This patch (of 2):
Instead of constantly checking each possibility of the maple state,
create a fast path that will skip over checking unlikely states.
Link: https://lkml.kernel.org/r/20230921181236.509072-1-Liam.Howlett@oracle.com
Link: https://lkml.kernel.org/r/20230921181236.509072-2-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Pedro Falcato <pedro.falcato@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| -rw-r--r-- | include/linux/maple_tree.h | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/include/linux/maple_tree.h b/include/linux/maple_tree.h index e41c70ac7744..f66f5f78f8cf 100644 --- a/include/linux/maple_tree.h +++ b/include/linux/maple_tree.h @@ -511,6 +511,15 @@ static inline bool mas_is_paused(const struct ma_state *mas) return mas->node == MAS_PAUSE; } +/* Check if the mas is pointing to a node or not */ +static inline bool mas_is_active(struct ma_state *mas) +{ + if ((unsigned long)mas->node >= MAPLE_RESERVED_RANGE) + return true; + + return false; +} + /** * mas_reset() - Reset a Maple Tree operation state. * @mas: Maple Tree operation state. |